1. Field of the Invention
The present invention relates to a filtering device for use in a system for processing photosensitive material
2. Description of the Background Art:
FIG. 1 illustrates a conventional system. The conventional system includes a processing solution container 2 having an outlet 8, an inlet 10, and a device 70 for circulating processing solution. The circulating device 70 is connected to the outlet 8 and the inlet 10. The container 2 may further include guide rollers (not shown) for holding and guiding a strip of film 7 through a transporting passage.
The circulating device 70 includes a pipe 72 connected between the outlet 8 and the inlet 10. Circulating processing solution passes through the pipe 72. A pump 4 is connected to the pipe 72 for applying pressure to the processing solution to circulate the same. A heating means 6 is connected to the pipe 72 for keeping the processing solution at a predetermined temperature. A filter 73 is connected to the pipe 72 for removing unnecessary materials such as sludge or dust caused by a chemical reaction, or the like, in the processing solution.
FIG. 2 illustrates a filter disclosed in Japanese Patent Laying-Open No. 75316/1985. The filter 73 of the prior art includes a filter case 74 connected to a pipe 72, and a filter 90 contained in the filter case 74. The filter case 74 is a cylinder having an opening at its upper end. The upper end is closed by a cover plate fixed by a bolt, a nut, or the like. A lower side of a hollow portion in the filter case 74 is provided with a partition plate 76 The inside of the filter case 74 is divided into a filtering chamber 78 and a collecting chamber 80 by the partition plate 76. Fixing cylinders 88 (having an equal diameter) are provided on the lower surface of the cover plate 82 and the upper surface of the partition plate 76. A cylindrical filter 90 is fixed in the cylinders 88. The filtering chamber 78 has an inlet 84 for the processing solution. The collecting chamber 80 has an outlet 86 for the processing solution. A central portion of the partition plate 76 has an opening by which the hollow portion inside the filter 90 communicates with the collecting chamber 80 when the filter 90 is fixed inside the case 74.
Referring to FIG. 1, the processing solution in the processing solution container 2 flows from the outlet 8 into the pipe 72. The pump 4 applies pressure to the processing solution to send it into the filter case 74. Unnecessary materials in the processing solution are removed by the filter case 74. The processing solution is heated in the heating means 6 to a predetermined desired temperature for processing photosensitive material and the heated solution is supplied through the inlet 10 into the container 2. The processing solution is agitated by circulation which results in high quality processing.
The processing solution flows into the filtering chamber 78 through the inlet 84. The processing solution passes through the filter 90. Then, the processing solution flows from the hollow portion of the filter 90 into the collecting chamber 80 through the opening at the center of the partition plate 76. Filtrate such as sludge or dust are removed while the processing solution passes through the filter 90. The filtered processing solution returns to the pipe 72 through the outlet 86.
When the filter should be replaced or cleaned, cover plate 82 is removed from the filter case 74. The filter 90 is taken out through the opening of the upper end of the filter case 74. A clean filter is fitted in the filter case 74. Then, the cover plate 82 is fixed to the filter case 74.
The conventional system has certain disadvantages. For example, since the filter case is connected to the circulating device, it is difficult to manufacture and maintain the system in good condition. In addition, in order to exchange filters, it is necessary to locate the filter case at a preferred upper, front or lateral position of the device by prolonging the pipe. Thus, the length of the pipe is increased and the arrangement becomes complicated. As a result, manufacturing and maintaining the device is difficult.
Another disadvantage is that since the filter case is connected to the pipe and since the filter case includes an opening for exchange of filters, leakage of the processing solution is liable to occur. Accordingly, leakage of processing solution may occur not only from a connection portion of the filter case and the pipe but also from the opening of the filter case when filters are exchanged. In addition, although the opening of the filter case is usually closed by the cover plate, solution may leak from this cover plate portion.
Still another disadvantage in the prior art is that filter exchange work is troublesome. At the time of exchanging filters, it is necessary to follow a sequence of complicated procedures such as securely closing the pipe connected at both ends of the filter, removal of the cover plate of the filter case with a tool, replacement of the filter with a new one, refixing the cover plate with a tool and reopening the pipe connected to both ends of the filter. These procedures take much time and must be performed without fail. For example, if one fails to reopen the pipe at either end of the filter after the exchange, the processing solution will not circulate and will not be filtered. Consequently, the quality of the processing solution will deteriorate and, since the processing solution is not stirred, processing of photosensitive material will be inferior. In addition, if the cover plate is not securely refixed, the processing solution might leak out from the filter case.
For these reasons, it is necessary to follow the proper sequence of procedures without fail at the time of exchange of filters. However, these procedures are troublesome.